BR102021002188A2 - PROPELLER BLADE, PROPELLER, PROPELLER INTEGRITY MONITORING SYSTEM FOR AN AIRCRAFT, AND, METHOD FOR MONITORING THE INTEGRITY OF AN AIRCRAFT PROPELLER - Google Patents

Abstract

A propeller integrity monitoring system for an aircraft, comprising: an aircraft having one or more propellers comprising a hub with an axis of rotation and a plurality of propeller blades, each blade comprising a blade body having a hub end and a tip end and a light source mounted in or on the blade body, the light source being capable of emitting a beam of light from the tip end of the propeller blade, wherein the light sources from each propeller blade are configured to emit a beam of light in a direction radiating outward from the propeller hub, wherein the system further comprises one or more receivers mounted in a fuselage and/or nacelle of the aircraft, each receiver having a sensor surface that is capable of to detect a position for each beam of light that crosses the sensor surface as the propeller rotates, so that the receiver generates a position-indicating signal as a measure of the blade tip trajectory for each passing propeller blade, wherein the system further comprises a processing unit that analyzes signals from the receiver to determine the integrity of the propeller blades of one or more propellers based on where the light beams from the propeller blades have crossed the surface of the sensor.

Description

PROPELLER BLADE, PROPELLER, PROPELLER INTEGRITY MONITORING SYSTEM FOR AN AIRCRAFT, AND, METHOD FOR MONITORING THE INTEGRITY OF AN AIRCRAFT PROPELLER FIELD OF THE INVENTION

[001] The present disclosure relates to a propeller blade, a propeller comprising a plurality of propeller blades, a system for monitoring the integrity of a propeller, and a method thereof.

FUNDAMENTALS OF THE INVENTION

[002] The propellers comprise a central rotating hub with a plurality of rotating blades, each mounted on the hub at one end and comprising a blade tip at the other. Each blade comprises a blade body with an airfoil section that creates thrust for an aircraft. As can be seen, propeller blades are crucial components of a propeller-powered aircraft and therefore need to be properly maintained. Propeller deterioration can significantly reduce the operating efficiency of a propeller and the resulting thrust of the aircraft.

[003] Aircraft propellers are therefore routinely checked before flight and require regular maintenance. The propellers can be damaged over time due to, for example, high load during abnormal propeller operations, adverse weather conditions, sand in the air, bird strike or the like. Blade degradation can occur leading to a loss of structural integrity.

[004] Pre-flight checks and maintenance are able to identify a damaged blade once the damage has reached a detectable level; however, these pre-flight checks may delay the aircraft's departure and maintenance may require the aircraft to be grounded for a significant period without notice. This can affect the operational efficiency of the aircraft. In most cases, pre-flight checks do not reveal any damage and therefore can be considered lost expenses.

[005] Therefore, it is necessary to provide a system that can monitor the integrity of the blades easily and in real time to assess whether maintenance is required.

SUMMARY

[006] According to a first aspect, there is provided a propeller blade comprising: a blade body having a hub end and a tip end and a light source mounted in or on the blade body, the light being able to emit a beam of light from the tip end of the propeller blade.

[007] The light source can be mounted close to one end of the propeller blade.

[008] The light source can be self-powered. The light source may be electrically connected to a piezoelectric device provided within the propeller blade in order to power the light source.

[009] The light source can be powered using the energy available in the propeller blade, optionally where the light source is electrically connected to a propeller blade de-icing circuit to power the light source.

[0010] The light source may be a laser device, optionally where the light source is a VCSEL.

[0011] According to a second aspect, there is provided a propeller comprising a hub with an axis of rotation and a plurality of propeller blades as set forth in the first aspect, wherein the light sources of each propeller blade are configured to emit a beam of light in a direction that radiates outward from the propeller hub.

[0012] Light sources can be configured to emit a beam of light in a generally radial direction.

[0013] The propeller may comprise de-icing devices in each of the blade bodies and electrical connections to couple electrical power to the de-icing devices of an electrical supply.

[0014] According to a third embodiment, a propeller integrity monitoring system is provided for an aircraft, the system comprising: an aircraft having one or more propellers as set forth in the second aspect, wherein the system further comprises one or more receivers mounted in a fuselage and/or nacelle of the aircraft, each receiver having a sensor surface that is capable of detecting a position for each beam of light that crosses the sensor surface as the propeller rotates, so that the receiver generates a signal that is indicative of position as a measure of the blade tip trajectory for each passing propeller blade, the system further comprising a processing unit that analyzes the signals from the receiver to determine the integrity of the propeller blades of a or more propellers based on where the light beams from the propeller blades have crossed the sensor surface.

[0015] The propeller health monitoring system may comprise a processor that processes this signal to determine a health state of a propeller blade associated with the signal.

[0016] The processor can determine a value for a trajectory of a blade tip of the propeller blade being observed

[0017] The processor may compare the value to a threshold value and/or a value for another propeller blade of the same propeller or a different propeller.

[0018] According to a fourth aspect, there is provided a method of monitoring the integrity of an aircraft propeller, the propeller comprising a hub with an axis of rotation and a plurality of propeller blades, each propeller blade comprising a body blade having a hub end and a tip end and a light source mounted in or on the body of the blade, the light source being capable of emitting a beam of light from the tip end of the propeller blade; wherein the method comprises: detecting, in a receiver comprising a sensor surface on an aircraft fuselage and/or nacelle, a position of the light beam crossing the sensor surface as the propeller rotates; generate a position indicative signal as a measure of the blade tip trajectory for each passing propeller blade and analyze the signals to determine propeller blade integrity based on where the light beams from the propeller cross the sensor surface.

[0019] The method may further comprise the step of determining a value for a trajectory of a blade tip of a propeller blade being observed.

[0020] The method may further comprise the step of comparing the value to a threshold value and/or to a value for another propeller blade of the same propeller or a different propeller.

BRIEF DESCRIPTION OF THE FIGURES

[0021] Certain modalities of disclosure are described below only by way of example and with reference to the attached figures, in which:
Figure 1 shows a propeller health monitoring system for an aircraft;
Figure 2 shows an aircraft propeller health monitoring system;
Figure 3 shows a receiver for use in a propeller health monitoring system when a faultless propeller is observed;
Figure 4 shows a receiver for use in a propeller health monitoring system when a propeller with a degraded propeller blade is observed;
Figure 5 shows a receiver for use in a propeller health monitoring system when a propeller with multiple degraded propeller blades is observed;
Figure 6 shows a receiver for use in a propeller health monitoring system during a variety of flight conditions; and
Figure 7 shows a method of monitoring the health of a propeller.

DETAILED DESCRIPTION OF THE FIGURES

[0022] Figure 1 shows a schematic diagram depicting a propeller-powered aircraft 100, where a propeller 102 is located on each wing of the aircraft. Each propeller 102 comprises a plurality of propeller blades 103. In the embodiment shown in Figure 1, the propeller 102 comprises 8 propeller blades 103, however, it will be appreciated that different numbers of propeller blades are possible. For example, the propeller may comprise 2, 3, 4, 5 or 6 propeller blades or more.

[0023] The propeller 102 can be any type of propeller. It may include, for example, a ducted propeller, an open rotor propfan motor, a pair of counter-rotating coaxial propellers or counter-rotating propellers.

[0024] Each propeller comprises a hub 105 on which propeller blades 103 are mounted. Propeller blade 103 may be integrally formed with hub 105, alternatively, propeller blades 103 may be mounted to hub 105 separately.

[0025] The propeller blades 103, therefore, each comprise a hub end 103a and a nose end 103b. Hub end 103a may comprise a blade root 107 for attachment to hub 105 of a propeller 102, an airfoil section or blade body 109 extending generally between hub end 103a and tip end 103b and a tip blade 111 at the outermost radial point of propeller blade 103. The propeller blade may comprise a fiber reinforced composite material.

[0026] The aircraft 100 shown in Figure 1 is provided with two propellers 102, however it will be appreciated that additional propellers may be present. For example, aircraft 100 may comprise four propellers 102, i.e. two on each wing or more than four propellers. Alternatively, the aircraft 100 may comprise only a single propeller 102, for example a rearward-facing propeller, where the propeller 102 is disposed between parts of a fuselage that extend beyond the propeller to support a tail section.

[0027] In operation, the propellers 102 of an aircraft 100 can be damaged due to, for example, high loading during abnormal propeller operations, adverse weather conditions, sand in the air, bird strike or the like. This can have an effect on the structural integrity of the propeller blade, particularly making the propeller blade less rigid, so it is necessary to perform regular maintenance checks on the propellers to check for such damage. These maintenance checks require the aircraft to be on the ground, which has a significant effect on the costs of operating the aircraft.

[0028] It is therefore desirable to provide a system and method that allows the integrity of the propeller blade to be monitored during flight in order to determine whether a maintenance check is required. This can help prevent maintenance from being scheduled when it is not needed. This can also allow degradation to be detected earlier, allowing for pre-ordering of replacement parts and pre-scheduling of maintenance.

[0029] In Figure 1, each of the propeller blades 103 of the propeller 102 is equipped with a light source 104. The light source 104 is fitted to the tip end 103b of each propeller blade 103 as shown; in particular, it can be fitted to the blade tip 111 of each propeller blade 103.

[0030] The light source can be embedded in a transparent resin inside the paddle body.

[0031] By "tip end" 103b of propeller blade 103 is meant that portion of propeller blade 103 which is positioned adjacent to and includes blade tip 111, for example where the pressure and suction surfaces are converging ( e.g. blade thickness is reduced) in a span/radial direction. This can be seen as representing the nearest third of the propeller blade tip, for example, and perhaps more precisely the last 20% of propeller blade 103 moving in the spanning direction of the hub end interface position 103a of the propeller blade 103 with hub 105 along blade body 109 to blade tip 111.

[0032] Each light source 104 is fitted to the propeller blade 103 so that it is configured to emit a beam of light 106 in an external and generally radial direction of the propeller 102. In this way, the light beam 106 can project a tip path of propeller blade 103 in another part of aircraft 100, such as the fuselage or nacelle, where a receiver 108 is mounted to detect the light beam 106 as the propeller rotates and the light beam 106 passes through the receiver 108.

[0033] As shown in Figure 2, the field of view 116 for the receiver 108 may vary in the top to bottom direction. For example, the field of view 116 may be in a range of ±30°, optionally in the range of ±20°, further optionally in the range of ±10°. This allows the receiver 108 to monitor the path of the light beam 106 over a certain range of distance. Although not shown in Figure 2, the field of view 116 of the receiver 108 can also vary within the same range of values in the front-rear direction.

[0034] The radial direction of the propeller 102 is the radial direction of the disk-shaped envelope traced by a blade tip 111 during one full rotation of the propeller 102 when no forward or aft loads are present. During operation, the propeller 103 will also experience loading due to thrust, for example, during take-off or a steep climb, or will experience resistance, for example, during landing or a dive, and this will cause the tip trajectory of the propeller blade change with the flight conditions. As the blade flexes and the path of the blade tip is moved back and forth during flight conditions, the light beam 106 and the path it traces over neighboring surfaces of the aircraft, such as the fuselage or a nacelle, also will be shifted back and forth by an amount proportional to the change in blade tip trajectory. Thus, by using light beam displacement 106, a measure of the change in blade tip trajectory can be measured and this can be used to assess the integrity of the propeller blades 103 once the propeller blades have deteriorated or have deteriorated. defect 103 will have lost some of their original stiffness and will exhibit a greater amount in the blade tip trajectory with different operating conditions.

[0035] The light beam can be configured to be emitted in a generally radial direction, so the precise direction can vary by ±20° in a circumferential direction and ±20° in an axial (front/back) direction.

[0036] It will be appreciated that the light source 104 may be located anywhere within or at the tip end 103b of the propeller blade 103, so long as the light beam 106 is not obscured in an outward, generally radial, direction. In other words, there must be a clear line of sight to the receiver 108 so that the receiver 108 can register the light beam 106. For example, although the paddle tip 111 may be the most appropriate position for the light source 104, so that the full movement of the blade tip is observed, the light source 104 may also be located in or on the blade body 109 in a position spaced from the actual blade tip 111, but in a location that can still observe the flex within the propeller blade 103, as this will still provide a measure of blade flexibility when changes are observed in the trajectory of the blade tip.

[0037] The light source 104 can be any device capable of transmitting a beam of light, for example a laser device or other type of light source that can generate a narrow and well-defined signal response in a receiver 108 as the light beam passes through a sensor surface of the receiver. In one example, the light source is a light-emitting diode (LED) or a laser diode, such as a vertical-cavity surface-emitting laser (VCSEL).

[0038] To account for the change in angle caused by the change in pitch of blade 103 of propeller 102, a resin light emitter can be used to maintain a constant flux intensity level.

[0039] In Figure 1, two optical receivers 108 are located on the outer surface of the fuselage 110, each receiver 108 having a sensor surface 108a that faces outward toward a propeller 102 and having a clear line of sight to the light sources 104 of an adjacent helix as the leading edges 103b of helix 102 pass. Optical receivers 108 are located so that they face and are generally flush with a portion of each propeller 102. They may be disposed on a surface of the fuselage or a nacelle which is disposed generally perpendicular to the incident light beam. 106 as it traverses the sensor surface; however, it does not have to be exactly perpendicular and angles of 20° or even 30° from the perpendicular can still produce acceptable readings. There may be as many optical receivers 108 as there are helices 102.

[0040] In the twin-engine aircraft 100 of Figure 1, there are two receivers 108 mounted on the fuselage 110, one on each side of the aircraft 100. In aircraft with four engines, the light sources 104 from the propeller blades 103 on the outer propellers can be blocked from fuselage-mounted optical receivers 108 due to internal propellers. In this case, optical receivers 108 for the outer propellers may be mounted in a nacelle of the inner propellers on one side of the nacelle facing the outer propeller.

[0041] Each receiver 108 may be mounted on the fuselage 110 or on the nacelle so that it is generally the same distance from the nose of the aircraft 100, in a longitudinal direction of the fuselage, as the corresponding propeller 102. The receiver 108 must have a portion of a sensor surface 108a arranged to detect the light beam 106 during one rotation of the helix 102, for example, the light beam 106 must cross the sensor surface 108a of the receiver 108 during each rotation of the helix 102 if it is to be detected. However, the exact longitudinal position of the receiver 108 will depend on the mounting position of the light source 104 with respect to the blade body 109 of the propeller blade 103 and the direction in which the light source 104 is configured to emit the light beam. 106. For example, there may be a degree of forward or backward tilt where the light beam 106 is emitted from a truly radial alignment. Positioning will also depend on the separation of light source 104 and receiver 108 during detection, as this can amplify displacement.

[0042] Receiver 108 is used to assess the change in blade tip trajectory during flight conditions. Receiver 108 may be positioned and have a sensor surface 108a such that it is capable of detecting a beam of light 106 from a propeller blade 103 through a complete bending range from the position that the beam of light 106 reaches when propeller blade 103 is faultless, over a full range of possible operating conditions, up to the point where light beam 106 can reach when propeller blade 103 has degraded from its manufacturing condition and exhibits a greater degree of flex. .

[0043] It is also envisioned that the receiver 108 and its sensor surface 108a may be arranged to detect only the light beam 106 when the propeller blade 103 is faultless, the absence of a signal from the receiver then indicating that the blade helix 103 has suffered a lot of degradation. Likewise, the receiver 108 and sensor surface 108a may be arranged to detect only when the propeller blade 103 has reached a threshold level of degradation, an absence of a signal then indicating that the propeller blade 103 is faultless. Receiver 108 may also comprise a plurality of sensors providing a plurality of sensor surfaces 108a. The plurality of sensor surfaces 108a can be used to detect different amounts of deflection.

[0044] To avoid any disturbances, the light emission may be outside the human visible spectrum. This reduces the risk to passengers on board the aircraft, in particular, it reduces the damage that can be done to their eyes.

[0045] The wavelength sensitivity of the receiver 108 may be responsible for the change in wavelength of the emitter due to atmospheric conditions.

[0046] Light source type may change depending on aircraft application. For example, infrared light cannot be used in military applications that require the use of Night Vision Systems.

[0047] Receivers 108 and light sources 104 may comprise de-icing capabilities. This prevents the formation of ice that can block or distort the beam of light emitted, which can lead to the corruption of the results.

[0048] In operation, as the propeller 102 rotates, the light beam 106 associated with each blade tip 111 is detected by the associated receiver 108 and a position is recorded. Figure 3 shows the sensor surface 108a of the receiver 108 with a trace 106a indicating where the light beam 106 crosses over the sensor surface 108a during a rotation of the propeller 103. The trace 106a will be present as a line perpendicular to an axis of rotation of the propeller 103, which follows a path drawn along the height of the receiver 108.

[0049] Trace 106a shown in Figure 3 provides a representation of the blade tip trajectory of a defect-free propeller blade 103 and is preferably positioned towards the middle of the sensor surface 108a during normal flight conditions.

[0050] On a defect-free propeller 102, each defect-free propeller blade 103 will generally have the same structural properties (subject to usual manufacturing tolerances and accumulated flight hours for the part). Propeller blades generally also experience the same load settings during operation and therefore all propeller blades 103 must exhibit a generally equal amount of deflection in the blade tip path during one rotation of the propeller 103 under a given set of conditions. of flight. Traces 106a for each light beam 106, i.e., for all propeller blades 103 of a defect-free propeller 102, can be substantially aligned to provide a single trace 106a, as shown in Figure 3 (assuming the light sources are all aligned).

[0051] Each receiver 108 on the aircraft, for example on one side of the fuselage or on one side of a nacelle, will observe a similar trace 106a for each light beam 106 (as shown in Figure 3 if the propeller blades 103 of the propellers 102 are without defects).

[0052] Figure 2 shows a detailed view of the propeller health monitoring system, comprising where the receiver 108 is connected to a controller 118. The receivers 108 will emit a signal based on where a beam of light 106 traces through of the sensor surface 108a. Image processing of the signal is then used by controller 118 to provide the output shown in Figure 3, which can provide an indication of any displacement in the path of the blade tip by detecting a displacement in the longitudinal position of trace 106a (for example, in a towards the front or rear of the aircraft). A processor 120 of a processing unit receives the output from controller 118 and can then be used to compare the signal to one or more of a previously recorded signal for propeller blade 103, a signal from another propeller blade and/or a theoretical signal or value, to determine the health status of the propeller blades 103.

[0053] Additional controllers 118 and processors 120 may be provided as redundancies in the event of failure of one or more of the controllers and processors.

[0054] Figure 4 shows the trace 106b across the sensor surface 108a of the receiver 108 if one of the blades 103 on a propeller 102 has deteriorated or been damaged. When a propeller blade 103 deteriorates or is damaged, its structural properties change, leading to a decrease in the stiffness of the propeller blade 103. As a result, under the same loading conditions, a deteriorated or damaged propeller blade 103, for example , a defective propeller blade experiences more deflection than a defect-free propeller blade 103. This can be measured in terms of a change in path from the blade tip to the propeller blade 103. A greater deflection in the tip path of blade indicates that the propeller blade 103 may have been damaged in some way or over time, and that an inspection or replacement may be appropriate.

[0055] The observed position of a damaged blade may be closer to the tail of the aircraft 100 during certain flight conditions and may be closer to the nose of the aircraft in other flight conditions, depending on whether the forces on the propeller blade 103 are pushing the blade tip in a forward or aft position in relation to the aircraft. The amount of deflection observed will therefore also depend on the operating conditions of the aircraft 100.

[0056] Shown schematically, the increased deflection of the damaged blade 103 may cause a separate detected optical trace 106b at a different location on the receiver 108, e.g. at a distance Δ from the detected optical signal 106a to the propeller good blades 103 102, as indicated in Figure 4. Distance Δ is determined by a processor to the receiver or to a central processing unit onboard aircraft 100, which receives data from optical receiver 108. Distance Δ corresponds to the difference in blade deflection 103 and therefore can provide a measure of the difference in blade tip trajectory compared to a defect-free propeller blade 103.

[0057] The propeller blades 103 associated with the output in Figure 4 refer to the same propeller 102 and, therefore, are subject to the same operating conditions. If all blades 103 were faultless, the output at receiver 108 would be indicative of trace 106a, as shown in Figure 3. Separate traces 106a, 106b indicate that a deteriorated or damaged blade 103 may be present.

[0058] Each blade 103 of a propeller 102 can be compared to historical values recorded for the propeller blade 103, to all other blades of the same propeller 102 and/or can be compared to a blade 103 in a diagonally opposite position on the hub 105.

[0059] Alternatively, each propeller blade 103 can be compared to a corresponding propeller blade 103 of another propeller 102 on the aircraft, e.g. a propeller 102 of the opposite wing, a propeller blade 103 located at the same hub position as the other propeller and/or can be compared to all propeller blades 103 of that other propeller, for example by an average value. This can be beneficial in identifying faults where multiple propeller blades 103 of a given propeller 102 have been damaged.

[0060] In another embodiment, the position of trace 106a for each propeller blade 103 can be compared to a threshold value for flight conditions.

[0061] The propeller health monitoring system may use all or any combination of the above to determine the health of a particular propeller blade 103.

[0062] In the case of a damaged propeller 102, the output of the receiver 108 may reveal two or more traces 106a, 106b, 106c, 106d caused by the light beams 106 traced on the sensor surface 108a at different longitudinal positions. During different flight conditions, due to increased deflection of a damaged or defective propeller blade 103, the blade tips 111, and therefore the light sources 104, may follow different blade tip trajectories relative to the propeller blades. no defects 103, depending on the extent of the damage.

[0063] In the event that multiple blades 103 have been damaged or deteriorated at different rates over time, the output of the receiver 108 may represent a set of traces 106a, 106b, 106c, 106d, each corresponding to a different longitudinal position. where the light beams 106 from the light sources 104 are traced through the sensor surface 108 of the receiver to each of the propeller blades 103. Each damaged blade 103 can be deflected by a different amount during operation, which can lead to to multiple traces 106a, 106b, 106c, 106d being received by receiver 108, for example, as shown in Figure 5. The extent of trace offset 106a, 106b, 106c, 106d may indicate that damage to some propeller blades 103 may be more severe than for others due to differences in propeller blade stiffness.

[0064] In order to determine if the additional traces 106b, 106c, 106d are the result of a damaged propeller blade 103 or if they were caused by excessive vibration or vibrations, the distances Δ1, Δ2, Δ3 can be evaluated along a defined number of revolutions and/or compared to a predetermined limit.

[0065] The distances Δ1, Δ2, Δ3 representing the displacement of traces 106b, 106c, 106d from the healthy trace 106a can be used to predict the remaining life of the individual propeller blades 103 and to determine the urgency of any maintenance.

[0066] If distances Δ1, Δ2, Δ3 are equal to or greater than a predetermined threshold, the integrity of the corresponding propeller blade 103 may be impaired.

[0067] In the present embodiment, the distances Δ1, Δ2, Δ3 are taken from a trace 106a of a defect-free blade 103 of the propeller 102, in order to quantify the deflection in the blade tip trajectory and therefore monitor the decrease in blade stiffness; however, as stated above, they can be compared to a corresponding propeller blade 103 on another propeller 102 of aircraft 100 and/or a predicted value based on a model.

[0068] The rotation position of the propeller 103 can be determined by a rotation sensor, for example from an Np/Beta sensor, so that the time of trace 106a crossing the surface of sensor 108a can be used to determine which propeller blade 103 the dash 106a represents in any instance.

[0069] This also means that if there is any variation in the location of trace 106a in a forward or aft direction of the aircraft due to variations in the positioning of light source 104 in relation to propeller blade 103 and the direction in which the light beam is emitted, then this can be explained by associating a base distance to a given propeller blade 103. The rotation position can also be used to filter the signals so that the receiver 108 can observe the relative displacement of a trace 106a for a particular propeller blade 103 to determine whether that blade is in a faulty or non-defective condition.

[0070] If it is determined that the integrity of one or more of the propeller blades 103 on an aircraft propeller 102 is impaired, it is necessary to identify the damaged blade. Using full authority digital engine control (FADEC) data, it is possible to determine, for example, the position of each propeller blade 103 on hub 105 at any time and map this information to the signals generated by receiver 108. The light beam 106 that is determined to represent a damaged blade 103 can then be assigned to a specific blade 103 in the propeller 102.

[0071] The light beams 106 may also be encoded in some way, for example with a signal that the receiver 108 can read and identify, in order to match the propeller blade 103 with the trace 106a seen on the receiver 108. Alternatively , the light beams 106 may have a different wavelength or color on each blade 103. The FADEC can therefore determine from the color/wavelength which blade may be damaged. As another alternative, a single beam of light 106 can be emitted at a time, allowing the FADEC to determine the deflection of each individual blade.

[0072] Typical minimum deflection distances Δ1, Δ2, Δ3 that indicate blade damage can be preset in the processing unit and can be any reasonable distance, taking into account any amplification in the observed distance resulting from blade bending, the separation of the receiver 108 and the angle of incidence of the light beam if not perpendicular. For example, the actual minimum blade tip trajectory deflection may be in the range of 2 mm to 10 mm. This can result in observed deflections where the light beams 106 are traced over the sensor surface 108a with between 20mm to 100mm, in a reasonably large aircraft.

[0073] The presence of a damaged blade 103 may be indicated to the aircraft crew and/or a maintenance alert may be issued. The system can operate in real time while the aircraft is in operation. Therefore, in the event that a propeller blade 103 is damaged, in response to the indication to the crew, the damaged propeller 102 can be turned off. This can help prevent further damage to blade 103 or the rest of the aircraft. Previously, when blades were only inspected at regular intervals, a damaged blade may have been used for longer flight hours, which could lead to further blade degradation and risk of failure.

[0074] The system of the present embodiment is even more advantageous as it provides a method of real-time monitoring of the integrity of the propeller. Previously, maintenance may have been performed on an undamaged 102 propeller, which could require an unnecessary landing, leading to increased aircraft operating costs. By monitoring the health of the propeller in real time, an alert can be triggered if the system determines that the integrity of the propeller blade may be impaired. Maintenance, therefore, can only be required if an alert is triggered, thus significantly reducing the time and cost of maintaining the aircraft.

[0075] Figure 6 shows an alternative system for monitoring the integrity of the propeller, which uses the same arrangement of transmitters 104 and receivers 108 as shown in Figure 1. The system shown in Figure 6 monitors different blades over a range of operating conditions, in contrast to the system shown in Figures 4 and 5, which compares changes in blade tip to blade trajectories under the same operating conditions. Thus, Figure 6 shows a receiver 108 with a sensor surface 108a for detecting light beams 106 transmitted by light sources 104. Depending on whether the propeller blades 103 are experiencing an overall load that is pushing the propeller blades to a stop. forward or backward direction, a predetermined acceptable range 114a on sensor surface 108a of receiver 108 can be set and if detected light beams 106 are received within this acceptable range 114a, then the system determines that the corresponding propeller blade 103 is No defects.

[0076] If the light beam 106 traces a path outside this acceptable range at the receiver 108, the processing unit may determine that the integrity of the propeller blade 103 is impaired.

[0077] The light beam 106 to the impaired propeller blade 103 may cross the sensor surface on either side of the area defined by the acceptable range 114a over a range of flight conditions, indicating that the blade tip 111 of the propeller blade 103 is deflected towards the nose and tail of aircraft 100 during these conditions.

[0078] This modality can be beneficial, as it is not necessary to compare the received optical signal 106 with that of a corresponding blade under the same operating conditions. This allows results to be provided more readily.

[0079] The acceptable band width 114a will depend on the separation of the light source and the receiver, ie the size and type of the aircraft and the propeller blade properties. The observed deflection width can, for example, be in the range of 10 mm to 80 mm.

[0080] The light sources 104 provided on each blade 103 may be powered by a piezoelectric power device provided on the propeller blade that uses vibrations of the blade in operation to generate energy for the light source 104.

[0081] Additionally or alternatively, the blade can be powered by electrical systems already present in the propeller blades, such as the de-icing system.

[0082] The light source 104 can be mounted to the paddle by any type of fastening means, for example by adhesive or fasteners. Alternatively, it may be formed integrally with the rest of the blade, for example embedded in resin during construction of the propeller blade.

[0083] As set forth in Figure 7, the method of monitoring the integrity of the propeller using the system described in this document comprises detecting 200 the position of a beam of light on a sensor surface of the receiver. The light beam is emitted by one of the light sources mounted on one or more of the propeller blades.

[0084] The method comprises generating 202 a signal which is indicative of the position of the light source. The signal is generated by the controller 118 and is used as a measure of the trajectory of the blade tip as it crosses the sensor surface of the receiver 108. The position of the light source on the sensor surface will differ depending on the deflection of the blade associated with the source. of light.

[0085] The method comprises determining 204 a value for the blade trajectory based on the signal generated by the controller 118. The value can be used to provide an indication of the deflection of the propeller blade. This value can then be compared 206a to a threshold value. The threshold value is based on a predetermined maximum deflection of a faultless propeller blade 103. If the value is outside the threshold, it is established 208a that the integrity of the propeller may be impaired.

[0086] Alternatively, the method may comprise comparing 206b the value to a value associated with another blade. The other blade can be on the same propeller or on a different propeller on the same aircraft. If the value is significantly different from the value associated with the other blade, it is established 208b that the integrity of the propeller may be impaired.

[0087] The present disclosure may also refer to a propeller blade comprising: a blade body having a hub end and a tip end and a signal source mounted in or on the blade body, the signal source being able to emit a beam of light from the tip end of the propeller blade.

[0088] As stated above, the signal source can be a light source. Alternatively, the signal source can be a magnet capable of interacting with a receiver using the Hall Effect.

[0089] The present disclosure may also refer to a propeller integrity monitoring system for an aircraft, comprising: an aircraft with one or more propellers, wherein the system further comprises one or more signal sources and one or more receivers mounted in an aircraft fuselage and/or nacelle. Each receiver has a sensor surface that is capable of detecting a position of the signal emitted by the signal source crossing the sensor surface as the propeller rotates, so that the receiver generates a signal that is indicative of the position as a measure of the tip trajectory. for each passing propeller blade, the system further comprising a processing unit that analyzes the signals from the receiver to determine the integrity of the propeller blades of one or more propellers based on where the signals from the signal source from the propeller blades crossed the sensor surface.

[0090] As stated above, the signal source can be a light source. Alternatively, the signal source can be a magnet and the receivers can be configured to use the Hall Effect to determine the position of the signal on the sensor surface of the receiver.

[0091] Signal sources can be mounted in the fuselage or nacelle of the aircraft. If the signal sources are fuselage or nacelle mounted, receivers can be mounted on the propeller blades.

Claims (15)

Propeller blade characterized by the fact that it comprises:
a shovel body with a hub end and a spike end and
a light source mounted in or on the blade body, the light source being capable of emitting a beam of light from the blade tip end of the propeller. Propeller blade according to claim 1, characterized in that the light source is mounted close to a tip of the propeller blade. Propeller blade according to claim 1 or 2, characterized in that the light source is optionally self-powered, wherein the light source is electrically connected to a piezoelectric device provided inside the propeller blade to power the light source . Propeller blade according to claim 1 or 2, characterized in that the light source can be powered using the energy available in the propeller blade optionally, wherein the light source is electrically connected to a de-icing circuit of the blade. propeller to power the light source. A propeller blade according to any preceding claim, characterized in that the light source is a laser device, optionally wherein the light source is a vertical-cavity surface-emitting laser, VCSEL ). Propeller according to any preceding claim, characterized in that it comprises a hub with an axis of rotation and a plurality of propeller blades, wherein the light sources of each propeller blade are configured to emit a beam of light in a direction radiating outward from the propeller hub. Propeller according to claim 6, characterized in that the light sources are each configured to emit a beam of light in a generally radial direction. Propeller according to claim 6 or 7, characterized in that the propeller comprises de-icing devices in each of the blade bodies and electrical connections for coupling electrical energy to the de-icing devices of an electrical supply. Propeller integrity monitoring system for an aircraft, characterized in that it comprises;
an aircraft having one or more propellers as claimed in claim 6, 7 or 8,
wherein the system further comprises one or more receivers mounted on a fuselage and/or a nacelle of the aircraft, each receiver having a sensor surface that is capable of detecting a position for each beam of light crossing the sensor surface in accordance with the propeller rotates, so that the receiver generates a signal that is indicative of the position as a measure of the trajectory of the blade tip for each passing propeller blade, wherein the system further comprises a processing unit that analyzes the signals from the receiver to determine the integrity of the propeller blades of one or more propellers based on where the light beams from the propeller blades have crossed the sensor surface. Propeller integrity monitoring system according to claim 9, characterized in that the propeller integrity monitoring system comprises a processor that processes this signal to determine an integrity state of a propeller blade associated with the signal. Propeller integrity monitoring system according to claim 10, characterized in that the processor determines a value for a trajectory of the tip of a propeller blade being observed. Propeller integrity monitoring system according to claim 11, characterized in that the processor compares the value to a threshold value and/or to a value for another propeller blade of the same propeller or a different propeller. Method for monitoring the integrity of an aircraft propeller, characterized in that the propeller comprises a hub with an axis of rotation and a plurality of propeller blades, each propeller blade comprising a blade body with a hub end, a tip end and a light source mounted in or on the blade body, the light source being capable of emitting a beam of light from the blade tip end of the propeller;
where the method comprises:
detecting, in a receiver comprising a sensor surface on an aircraft fuselage and/or nacelle, a position of the light beam that crosses the sensor surface as the propeller rotates;
generate a position indicative signal as a measure of the blade tip trajectory for each passing propeller blade
and analyzing the signals to determine the integrity of the propeller blades based on where the light beams from the propeller cross the sensor surface. Method according to claim 13, characterized in that the method further comprises the step of determining a value for a trajectory of a blade tip of a propeller blade being observed. Method according to claim 14, characterized in that the method further comprises the step of comparing the value to a threshold value and/or to a value for another propeller blade of the same propeller or a different propeller.

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